PSI - Issue 68

Xingling Luo et al. / Procedia Structural Integrity 68 (2025) 694–700 Xingling Luo et al. / Structural Integrity Procedia 00 (2025) 000–000

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of CGI under high temperatures. Besides, Zhan et al. (2022) conducted an in-depth study on the unit inclusion cells and larger RVE models to validate the hypothesis that an inclusion of any morphology can be replaced with a circular one in simulations. They also found that the effective properties calculated for the unit cell do not match those obtained from the large RVE in any case. Numerical simulations are often based on, and validated with, experimental tests. The conventional testing method is used to accurately measure the material response to imposed loading and environmental conditions such as strain, stress or temperature (Covaleda et al., 2020). These methods are suitable for the assessment of macroscopic mechanical properties of materials. Additionally, it is difficult to precisely monitor the microstructural changes occurring during the test. However, they not only require microstructural characterisation before and after the test but also considerable efforts to control the microstructural windows of interest. In contrast, in situ tests aim to monitor the microstructural changes during the experiment (Bjørheim et al., 2022). Although this is an ideal technique for studying local microstructural changes, they are more expensive, complex, and limited by the sample size. Hence, a reasonable use of both methods allows the study of the impact of the CGI microstructure on its macroscopic properties, while also providing data on the evolution of crack in CGI. Although mechanical properties and damage mechanisms of CGI have been investigated in recent years, a review on predicting mechanical properties and crack propagation of CGI using different types of numerical simulations is still limited, due to its complex microstructure. Besides, understanding the interaction of propagating cracks with this complex microstructure is crucial for the enhancement of the structural integrity and performance of components made from CGI. Hence, this study seeks to provide a comprehensive overview of the research approaches developed by the authors. Different numerical methods were considered to investigate the influence of microstructure (in terms of graphite particle morphology) on the mechanical properties and failure behaviour of CGI. Four different types of models based on microstructure characteristics - (1) single inclusion; (2) two inclusions; (3) real and simplified morphology based on SEM images, and (4) random distributions of inclusions - are compared in this study. Besides, two experimental approaches, in situ tensile testing with an optical high-speed camera, and conventional testing methods were also employed to validate these models. The overall structure of this study is illustrated in Fig. 1.

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Fig. 1. Overall structure of numerical and experimental approaches employed.